1. Field
Apparatuses and methods consistent with exemplary embodiments relate to restoring color of an image obtained from a multi-spectral filter array (MFA).
2. Description of the Related Art
An image is obtained from a multi-spectral filter array (MFA) so as to simultaneously obtain natural color, detailed information regarding a near infrared (NIR) band, or improved sensitivity in a night environment.
To this end, resolution of each channel image should be improved and color thereof should be restored. In particular, color restoration in an MFA image processing operation should precede essentially. In this regard, research of converting an input image into a photo with a user's desired tone and atmosphere has proceeded. The purpose of this research is to pursue color transfer based on an analysis of characteristics of the input image and a target image. That is, a technique for pursuing color transfer by analyzing a statistical color distribution on each image based on similarity between two images (input image and target image) has been studied.
For example, there is a color transfer method in the same color space, like color transfer, whereby an image in a visible light band is transferred into another image in the visible light band. However, in the color transfer method, color is greatly damaged when color transfer is performed in different color spaces.
Also, when a signal-to-noise ratio (SNR) is considered in a color restoration process, there is a trade-off in which details of an image are damaged or color restoration performance is lowered. In detail, when the relative importance of the SNR is assumed to be higher than actuality, color restoration performance is maintained but the SNR is not maintained. Thus, components that damage low frequency signals may be generated in a flat region or details of high frequency signals may be damaged. Unlike this, when the relative importance of the SNR is assumed to be lower than actuality, the relative importance for performing the color restoration process decreases. Thus, there is a large tendency of maintaining original signal components and details of an input image and components of the flat region are well preserved, but a chroma of color is greatly lowered than actuality.